Printing machine



Sept. 21, 1937. J. W. BRYCE ET Al. 2,093,545 4 PRINTING MACHINE lFiled Oct. 25, 1933 6 Sheets-Sheet l all.: llll Il I EL MAIN Salani- HIIHHIHIIIIIIIIIIIIIIIIIIIHIII FIG.1.

. ATTORZY- PRINTING MACHINE Filed 001;. 25, 1953 6 Sheets-Sheet 2 ORS Sept. 21, 1937. J. w. BRYcE ET AL PRINTING MACHINE Filed Oct. 25. 1953 6 Sheets-Sheet 3 WON Sept. 21N, 1937. .1. w.' BRYCE ET AL 2,093,545

PRINTING MACHINE Filed oct. 25. 1955 e sheets-sheet 4 F IG 6 I I o Rs 1 /230 1 253 224\ --An" l l 5 l zaai;

237 232 240 2"- 23 L MMiJ. (l1-:H l l l L.. 227 24a- 228 '6 226 243 27 'sa 226 19a o '11 T Y k a0 al 50 f, OOO Q OO@ OG G OOO (D O l (19 FIG. 7.

' ARC 235 TSC ATTORNEY Sept. 2l, 1937. J. w. BRYCE ET AL 2,093,545

4 f PRINTING MACHINE Filed Oct. 25. 1953 6 Sheets-Sheet '5 Fla-.9. I

NRC NRS orf y nu sept.- 21, 1937. J. w. BRY'CE ET AL 2,093,545 d PRINTING MACHINE Filed oct. 25, 1955 e sheet's-sheet 6 :2o l A I W5 i OR. n

ATTORNEY Patented' sept. 21, 1937y UNITED STATES PATENT OFFICE PRINTING MACHINEl Application october 25, 193s, sei-m1 No. 695,090

35 claims. (01. lsv- 12) This invention relates to typewriting machines in general.

The broad object is to generally improve type- Writing machines by making them simpler in construction, cheaper to build, and more reliable intheir operation.

Another broad object is to provide a power driven typewriting machine whichxis completely electrically controlled by keys.

A further object is toprovide a typewriting machine wherein printing is effected by a single type wheel which rotates continuously and whose motion is notinterrupted even when the impression is made from a type element on the wheel.

Still another object is to provide a typewriting machine wherein the printing mechanism', letter spacing mechanism, back spacing mechanism, and case shifting mechanism are constructed as a simple compact unit movable axially of the platen.

Another broad object is to provide a typewriting machine with a printing mechanism capable of printing clearly while the platen and types are moving relative'to each other in a letter spacing direction.

Still another broad object is to provide a typewriting machine adapted for use in connection with printing telegraph systems and automatic letter writing machines A further broad object is to provide a power driven, electrically controlled typewriting machine which has considerably fewer working parts than prior machines of this type.

Another broad object is to provide a typewriti'ng machine which has few oscillating or reciproeating parts operating at high speed and is practically free of the bad effects of inertia which limit the speed of machines having type bars and the necessary operating linkages for the type bars.

A specic object is to provide an improved electrically controlled combined letter spacing and back spacing mechanism which also functions to produce tabulating movement of the printing unit and to return the latter to starting position Some of the more specific objects are toprovide mechanisms or means for performing and/or controlling the following functions.

Automatic repeating of any selected character as a result of a single depression of vthe desired key;

Preventing the repeating of a character when its key is held depressed by the operator;

Selective control of the last two functions;

Automatic repeating of any selected character as many times as desired with a niunber of automatic returns of the printing unit to starting position intervening one or more times;

Preventing two keys from being depressed in rapid succession Without a printing operation under control of the lrst key depressed;

Preventing printing operations while the printing unit is in motion for tabulating purposes or being returned to begin a new line of typewritten matter;

Adjusting the point at which operation of the letter spacing mechanism commences;

Preventing the letter spacing operation from l taking place before a printing operation takes l place;

Automatically locking the machine against operation when current is turned 01T, whether accidentally or intentionally;

Shockless movement of the printing unit' from one position to` another;

Locking a selected character key in-,depressed position until the character has been printed.

Various other objects, advantages, or features will be pointed out in the following description and claims or will be apparent after a study of the description, claims, and drawings.

In the drawings:

Fig. 1 is a plan view of the machine.

Fig. 2 is a vertical section taken on the line 2 2 in Flg. 1.

Fig. 3 is a vertical section on the 1ine`3--3 in Fig. 1.

Fig. 4 is a vertical section on the line 4 4 in Fig. 1.

Fig. A5 is a vertical section on theline 5-5 in Fig. ,4 with certain parts broken away.

Fig. 6 is a front elevation of the stop bar and related parts.

Fig. '7 is a vertical section on the line 1-1 in --Fig. 6.

Fig. 8 is a detail view showing various control stops in perspective.

Fig. 9 is a diagram of the electrical connections.

Fig. 10 is a fragmentary view of the rear face of the type wheel, that is. as viewed from the left in Fig. 2.

Fig. 11 is a horizontal section taken on the line lI-ll in Fig. 10.

Fig. 12 is a vertical section taken on the line i2-l2 in Fig. 1U.

Fig; 13 is a large scale elevation of the spacing clutch.

Fig. 14 is a plan view of the clutch illustrated in Fig. 13.

Main framework The various mechanisms of the typewriter are supported by the main frame which comprises side frames I8, Ii (Fig. 1) which are joined to form a rigid framework by cross bars I2, I3, and i4 (Fig. 2) and a top frame casting I5. The latter, together with the side frames I0, ii, a bottom plate i5, a front plate I1 and a rear plate i1a, form a housing which is tight enough to exclude dust.

Other cross bars or frames designated i8, i9, 20, and 2|, further strengthen the main frame and also support various-mechanisms and contacts to be described more fully later. These latter cross bars or frames with the mechanisms carried thereby are intended to be removable as units in order to facilitate assembly and repair.

Keyboard The machine is completely controlled by a standard four-row keyboard generally designated 22 in Figs. 1 and 2. Besides the usual forty-two character keys there are the space bar 23, two shift keys 24, a shift lock key 25 of usual construction, a back space key 26, a return key 21, a line space key 28, and a tabulating key 29. Each key has a key lever 30 (Fig. 2) pivoted on a cross rod 3| which is journalled in lugs |9a formed in the cross bar i9 (see Fig. 6 also). Compression springs 32 hold the free ends of key levers 30 against a stop bar 33 secured tothe rear face of the cross bar i4, a comb 34, also se-,

cured to said bar I4 guiding the free ends of the keys. Each key lever 30 has several lugs of dllerent shapes formed therein.

The lug 35 of each character key lever 30 overlies and operates a pair of contact members 36 carrying contacts like Kb (Fig. 2*) which control the printing of. the character corresponding to the particular key which may be depressed. Thus, the contacts Kb in Fig. 2 are closed whenever the B" key is depressed. The contact members have insulating buttons 31 upon which the lugs 35 press and are mounted on the cross bar 2U. The lower contact members 35 are insulated from the bar 20 and from the upper contact members but make contact with a common bar 38 which corresponds yto the left-hand wire in Fig. 9. This bar 38 greatly simplifies making the electrical connections of the machine and avoids a tangle of wires in the base of the machine where space is necessarily limited. The key levers 30 of keys 24, 26, 21, 28, 23 also control contacts like Kb.

The lug 39 is shaped like a hook and cooperas with a locking bar 40 which is common to all the character key levers 30 and is plvoted like at 4i tothe side frames i8, il. Lugs 39 are not provided in the cases of the two key levers 88a carrying the space bar 23 and the key levers of shift keys 24, return key 21, line space key 28, back space key 28. and tabulating key 23, but are present only on the 42 key levers corresponding to character keys. The bar 4I is held against stop pins, like 42 (Fig. 2) on each frame in, Il, by a, spring and whenever a character key is depressed its lug 39 hooks under the bar 4U holding the key depressed until the bar 40 is rocked by a release magnet RM to release the depressed key.

The lug 43 rides in slots in a pair of comb plates 44 which support a key arresting device of any desired type which permits only one key to be depressed at a time. Lugs 43 are not present on the case shift key levers as it is necessary to hold one of the case shift keys and a character key depressed to print an upper case character. 'I'he combs 44 are mounted on the cross bar 2i.

The lug 45 is at the end of each key adjacent the bar i4 and overlies a bar 46 pivoted, as at 41, to the side frames ii), Ii and held by springs like 48 against stops like 49. A magnet LM, hereinafter called the locking magnet, is adapted to rock the bar 46 to remove the latter from beneath the lug 45 and permit any key to be depressed. The magnet LM prevents depression of a key when the supply of current is cut ofi as by opening the main switch MS (Fig. 9), a dead power line, or the pulling out of the connector plug P from its receptacle. This prevents misprints which might result from accidental depression of a key while the current is cut oiT.

Mounted on a cross rod 50 beneath the righthand ends of all the character key levers 3U is a bail comprising a cross rod 5i and arms like 52 secured to the rod 50 which is journaled in the frames I0, Ii and urged upwardly by torsion springs against the lower edges of the key levers 30.

The arm 52 adjacent side frame il is extended to the left (Fig. 2) and underlies an insulating button on one member of a pair of contact members 53 carrying contacts NRC. The mem- A bers 53 are mounted on and insulated from a bracket secured to the right side frame ii and their contacts NRC will be termed the non-repeat contacts hereinafter as their function is to prevent repeated imprints in case a character key is held depressed by the operator for too long a period.

The rlngerpeces of the keys are not permanently secured to the vertical stems 54 of key levers 3D but are frictionally held in place peri mitting the stems 54 to be inserted through suitable openings in a plate 55 whichA excludes dust. The plate 55 also supports the main switch MS (Fig. 1)', non-repeat switch NRS, and automatic repeat switch ARS. The functions of the last two switches will be explained later herein.

Power drive Power to operate the machine is furnished by a motor M, mounted adjacent the left side frame i0 (Fig. 1), which motor, through suitable gearing, drives a vertical shaft 56 journaled in suitable bearings on the frame i0. Bevel gears 51, (Fig. 1) connecting shaft 58 and a cross shaft 58, cause a commutator assembly 59 (see Fig. 9 also) to be rotated in a clockwise direction (Fig. 2) while bevel gears 60 (Fig. l) on shaft 56 and a shaft 6i cause the latter to rotate a shaft 62 through other bevel gears 63. The shaft 58 does not extend as far as the right side frame il, but is journaled in a suitable bracket i8a carried by the cross frame i 8. As the details of the bearings for shafts 58, 58, 5I, and 62 are of little importance they have not been illustrated. A suitable cover 84 protects the fingers of the operator from the gears 51, 88, 83 and also prevents scattering of lubricating oil. The shaft 82 furnishes power to operate the printing unit 65 in its movements axially of the platen 66.

Platen and paper guide The platen 88 (Fig. 2) is secured to a shaft 81 journalled in housings B8, 68 (Fig. 1) formed in the top frame casting I5. The housings 68 68 are at theV ends of an opening formed in the front part of casting I5 into which opening the platen 86 extends. Extending partly around the platen 66 is a paper guide 18 secured to an inclined face 1| of frame casting I5, which face 1| constitutes the rear wall of the opening just mentioned. The paper guide has a number of openings through which project pressure rollers 12 carried by shafts 13 journaled in arms 14 pivoted in a cross shaft 15. The latter is mounted on the side frames I0, and carries torsion springs like 16 which engage the arms 14 in such fashion as to normally hold rollers 12 against the platen 66, The ends of shaft 15 are seated in notched blocks 11 secured to the side frames I8, With this construction the machinemay be partly disassembled for cleaning and repairs by first removing the top framegcasting I5 supporting the platen 66 and then lifting out the shaft 15.

Line spacing mechanism The platen is rotated one or more line space distances by mechanism operated by a line space solenoid LSS (Fig. 3) which is mounted on the i right-hand side frame (Fig. 2). The solenoid LSS actuates a link 18 (Fig. 3) pivoted to one.`

arm of a bell crank 18 rigidly mounted on a short shaft (not shown) which is coaxial with shaft 58 and journaled in the right side frame I and also in the bearing in arm |8a which supports shaft 58. The shaft carrying bell crank 18 also has secured thereto an arm 88 connected by link 8| to one arm of a bell crank 82 loosely mounted on the platen shaft 81.

The other arm of bell crank 82 carries a' spring pressed pawl 83 which is adapted to engage the teeth of a ratchet wheel 84 secured to shaft 81. A spring 85, secured to an arm of bell crank 18, normally holds the parts in the, position of Fig. 3 wherein an arm of bell crank 18 abuts an adjustable stop 85 mounted on side frame II.

Einergization of line space solenoid LSS causes link 18 to be drawn downwardly, rocking bell crank 18 and arm 88 in a clockwise direction..

moving link 8| upwardly, and rocking bell crank 82 in a counterclockwise direction with the result that pawl 83 will engage the teeth in ratchet 84 and rotate said ratchet wheel until the end of the pawl engages a stop pin 81 which acts to prevent further movement of both thev pawl and the ratchet.

Normally the pawl 83 is held out of engagement lwith ratchet 84 by-a cam 88 forming part of a line space control lever 88 which extends through a slot 88 in the top frame casting I5 within convenient reach of the operators right hand. The cam 88 governs the distance the pawl 88 must move before it can engage the ratchet wheel 84 and thus controls the number of line spaces of movement imparted to the platen 85. When' the lever 88 and cam 88 v are in the position 8 of Fig. 3 the platen will receive its maximum movement, or three `line spaces, as the pawl will move ratchet wheel 84 the distance between four consecutive teeth. When lever 88 is in positions I and 2, the platen will be moved one and two line spaces, respectively. A spring pressed detent 8|, pivotally mounted in a bracket 82 secured to the frame casting I5, has three notches co-operating with a pin 83 carried by lever 88 to hold the latter yieldingly in any one of its three posil tions. A spring operated arm 84, pivotally mounted in a bracket 85 secured to frame I5, carries an aligning roller which is held between the teeth of ratchet 84 by a spring 86 connected to arm 84 and a pin 81 secured to frame casting I5. The roller in arm 84 holds the ratchet 84 and the platen 66 against accidental displacement while a line is being typewritten but yields readily to movement of the ratchet wheel 84 by pawl 83.

The manner in which the line space solenoid is controlled will be explained hereinafter. The usual manual feed knobs 81 are provided for turning the platen by hand and are secured to the ends of shaft 81.

Printing unit The printing unit 65 is best illustrated in Figs. 2, 4, and 5 and its framework includes side frames 88, 88 and a central frame |80 all secured to grooved bars |0| which hold the three frames in spaced relation. Four sub-frames |02a to |82d are secured to the frames 88, |08 and support various shafts in the compartment formed between the frames 88, |88. A back plate |83 of thick sheet metal, a front plate |84, and a top plate |85 0f thinner metal, together with the side frames 88, 88 form a'box-like housing which protects the printing mechanism against dust and tampering.

The printing unit 65 is mounted on suitable anti-friction bearings which may consist of balls or rollers carried by the grooves in bars |8| and similar grooves in four parallel rails |86 rigidly mounted in the frames I8, II. Thus, the printing unit is movable transversely of the machine, that is, parallel (with the platen. The mechanism for producing suchl transverse movement will be described more in detail hereinafter.

The,frame |8 (Fig. 2) extends parallel with the bars |88 and, besides supporting the right hand end of the shaft 58 as described, also supports a number of contact bars I 81 which cooperate with metallic contact strips or brushes |08 mounted on the back plate |03 of the printing unit. By this means the various control magnets and contacts carried by the printing unit 65 are connected to the magnets and contacts carried by the main framework of the machine. As will be seen in Fig. 2, the contact bars |81 are separated from each other and frame |8 by flat strips' |88 of insulating material which are much wider than the contact bars to provide deep grooves into which extend the brushes |08. This construction prevents the operator's fingers from accidentally touching the live contact bars while the machine is in operation'.

The contact bars |01 and insulating strips |88 may be secured to the top edge of frame I8 by long screws ||8v which screws pass through holes in the contact bars and strips and are insulated from the contact bars by washers or collars of insulating material. The brushes |08 are mounted in rectangular notches in a block of insulating material by means of terminal s crews ||2 which extend into the interior of the printing unit. The block is set in a rectangular opening in the back plate |88 and secured Fig. 2. It includes a type wheel ||4 secured to a shaft I5 which is rotatably and slidably mounted in frames 98, 99, |00. The type wheel ||4 is within the compartment between frames 90, 99 and comprises a flanged disc ||6 (Figs. 10, ll, and l2) having 42 radial grooves ||1 milled in the flanged part of the disc. In grooves ||1 are slidably mounted 42 type elements ||8 each bearing one of the upper case characters, that is the .capital letters and certain special signs, punctuation marks, and so on. The grooves ||1 are deep enough and wide enough to permit the type elements to slide freely when a ring ||6a is clamped to the side of the flange in disc ||6. Each type element ||1 has a recess ||9 into which extends a rectangular block |20 secured in a rectangular hole breached in the disc ||6. The blocks |20 act as stops to prevent removal of the type elements ||9 when ring ||6a is secured to the side of disc ||6. A spring |2|, contained by each recess ||9 and interposed between block |20 and the right hand shoulder of such recess ||9 (Fig. 12), normally holds each type element in the position of Figs. 2 and 12 with the lefthand shoulder abutting block |20 in which position the type is out of contact with platen 66.

Ring |6a is similarly provided with 42 grooves ||1a in which are mounted type elements ||8a bearing the lower case characters. 'I'he type elements ||8a have associated therewith blocks |20 and springs |2| exactly like those associated with type elements IIB. A ring ||6b retains the type elements ||8a in their grooves and the two rings ||6a, |61) are rigidly secured to disc ||6 by a number of screws |22 to form a compact type wheel unit.

The type wheel ||4 is rotated by means of a gear |23 secured to shaft ||5 through a train of gears which comprises an idler gear |24 journaled on a screw stud |25 carried by a central frame |00 which idler, in turn, meshes with a gear |26 secured to a sleeve |21. The latter is slidably mounted on shaft 62 and extends between the side frames 99, 99 through a hole |28 in central frame |00. Mounted on the sleeve |21 between frames 98, |00 is a driving element 29 which has the general shape of a ratchet wheel. The hub of the driving element |29 is slotted as is the case with the sleeve |21, and secured to the side of the driving element 29 is a key |30 which extends through the slots in said sleeve |21 and the hub of driving element |29 into a key-way in shaft 62. It is clear that, as long as shaft 62 is turning, the sleeve |21, driving element |29, and gear |26, and hence type wheel ||4, will be rotated and the printing unit may be moved to the right or to the left (Fig. 1) without disturbing the driving connection. The printing wheel is constantly rotating while the machine is being used and never stops rotating even for the very brief space of time during which an impression is being made by a selected type element.

An impression is taken from a selected type element by means of a printing hammer ,|3I which is pivoted on a stud |32 carried by frame 98 and is held by a spring |33 against an adjusting screw |34 carried by a lug secured to the frame 90. The printing hammer |3| is bent in such fashion as to extend into the space formed by the flange ||6 and rings ||6a, ||6b. Normally the upper or striking end of the hammer |3| is in the plane containing the longin tudlnal axes of the lower case type elements |8a and is adapted to strike the right-hand end of any type element ||8a which may have its lto release the end |39 of bell crank |40.

character at the printing point whenever the printing hammer is operated.

The printing hammer |3| is operated by movement of driving element |29 through mechanism which is controlled by a printing magnet PM secured to the left side of the central frame |00.

The armature of magnet PM is secured to the upper end of a lever |35 pivoted at |35a to' frame |00. The lower end of lever |35 is connected by a link |36 to one arm of a two-arm latch lever |31 pivoted at |38 to frame 98. One arm of lever |31 is hook shaped and engages the extreme right end |39 of a bell crank |40 pivoted at |4| to frame 98. A spring |42, interposed between one arm of bell-crank |40 and latch lever |31 holds the parts in the position of Fig. 2 where the end |39 of bell crank |40 is held up by the hook shaped arm of latch lever |31 and a lug |43 forming part of bell-crank |40 does not quite engage the lug |44 of latch lever |31.

A driving member |45 shaped like a bell crank j is pivoted on the upper end of a lever |46 and to the vertical arm of said driving member is connected the spring |33 which tends to hold the horizontal arm |41 of driving member |45 against a round nosed lug |48 in bell-crank |40. The arm |41 has a hook shaped lug |49 which is out of the path of movement of the teeth in driving element |29 when the parts are in the position of Fig. 2.

The lever |46 is pivoted at its mid-point on a short shaft |50 journaled in the frames 98, |00 and the lower end of said lever is connected by a link |5| to the lower end of a lever |52 pivoted at its mid-point on a shaft |53 similar to shaft |50 I and also journaled in frames 98, |00. The upper end of lever |52 has arounded nose |54 abutting a similar nose |55 an arm |56 forming part of type hammer |3| and extending below stud |32. The link |5| has at its right-hand end (Fig. 2) an offset lug carrying an insulating block |51 which is adapted to engage the bentover end of one member of a pair of spring contact members |58 carrying contacts SC. The contact members |59 are mounted on a lug |59 offset from a plate |60 which is adjustably mounted on frame |00 as by screws |6| extending through a slot in plate |60. Normally the contacts SC are separated, as in Fig. 2 and will be termed the spacing contacts hereinafter since their function is tocontrol the letter spacing movement of the printing unit which takes place after each character is printed.

The operation of the parts just described will now be explained briefly. When magnet PM is energized the link |35 is drawn to the right (Fig. 2) rocking latch lever |31 counterclockwise The combined action of spring |42 and lug |44 forces driving member |45 downwardly until lug |49 gets between the teeth of driving element |29 and is positively engaged by one of said teeth. As a result, driving member |45 will be drawn to the right (Fig. 2) rocking levers |46, |52 in a clock wise direction and, through the noses |54, |55. rocking the printing hammer |3| in a counterclockwise direction, to propel the upper end of the printing hammer against the right-hand end of the type element ||8 or IIBa which may be at the printing point. This will cause the type in the selected type element to make an impression on the work sheet.

The right-hand end of driving member |45 is guided in an inclined slot |62 in a block |63 adjustably secured to the central frame |00 which slot acts to cam the right-hand end of member |45 upwardly to disengage lug |49 from the teeth of the driving element |29. The parts are so proportioned that the movement of the printing hammer |3| is extremely rapid and the selected type element is struck a, very quick blow while the type wheel |4 is actuallymoving. The speed of operation ofthe printing hammer is so vgreat that the type element makes its impression and is Withdrawn practically instantaneously without affecting the motion of the type wheel ||4 or causing a blurred impression.

During movement of member |45 to the right under the influence of driving element |29 a lug\-" |64 on arm |45 will engage lug |48 and cam the right-hand end of bell crank |40 slightly upwardly (Fig. 2). When slot |62 becomes effective to cam the right-hand end of arm |41 upwardly as described, the right-hand end of bell crank |40 will be rocked a further distance upwardly until the end |39 of bell crank |40 is in a position slightly above the hook in latch |31 and is in readiness to be reengaged by the latter.

The lugs |43, |44 cooperate at this time to force the latch lever |31 into latching position and also force the armature of the magnet PM away from the poles of said magnet in case residual magnetism holds the armature against the poles. The spring |33 restores the printing hammer |3| and driving member |45 to the position of Fig. 2, the lug |64 being so proportioned and located with reference to lug |48 that restoration of member |45 is permitted without interference between lug |49 and the teeth in the driving element |29.

The manner in which magnet PM is controlled to print the proper character will be more clearly explained hereinafter.

Any suitable inking means may be used to produce the impression of the type on the paper, such as an inking ribbon |65, and any convenient ribbon feeding mechanism may be employed. The means for inking the type forms no part of the present invention and details of such means have been omitted from the drawings.

The compartment in the printing unit between the frames 99, |00, contains the mechanism for moving the printing unit axially of the platen to space after each impression, or letter spacing to use the common expression, and reversely moving the printing unit or back spacing as it is called. The mechanisms just mentioned are also used to cause tabulating movement and return the printing unit to starting position to begin a new line. All these mechanisms are electrically controlled and operated by shaft 62.

Secured to sleeve |21 between frames 99, |00 is a bevel gear |66 which meshes with two bevel gears |61, |68 xed on shafts |69, |10 journaled in frames |02a, |021), |02d, and plates |03, |04. Secured to Shafts |69, |10 adjacent the back plate |03 and front plate |04, respectively, are pinions |1|, |12 which mesh with idler gears |13 loosely mounted on a shaft |14 journaled in the plates |03, |04 and frames |02a, |02d. The idler gears |13, in turn, mesh with gears |15, secured'to' shafts |16, |11 journaled in back plate |03 and frame |02c, and front plate |04 and frame |02d respectively. Secured to the shafts |16, |11.are driving elements |18, |19 which may take the form of ratchet wheels. It is quite plain that the driving elements |18, |19 Will rotate continuously when motor M is in operation. Loosely mounted on shafts |16, |11 adjacent driving elements |18, |19 are discs |80 which have the general shape shown in Fig. 13 which illustrates the construction of the left-hand disc` in Fig. 4. Pivoted on each of these discs is a driving pawl |8| having a lug |82 adapted to engage the teeth of the driving elements |18, |19.

A spring |83, secured to a pln carried by each disc and to the free end of the associated driving pawl |8I, normally tends to draw the pawl |8| toward the center of the disc 80 so as to force lug |82 between the teeth of the adjacent driving element. Such action is prevented, however, by coaction of an offset lug |84, formed in a rock lever |85 pivoted on a bracket |86, with the tali |81 of the driving pawl thus holding said pawl in the position shown in Figs. 5 and 13. A torsion spring |88 engaging bracket |86 and the lever |85 below its fulcrum, normally holds the lever |85 in the position of Figs. 5 and 13 with lug |84 engaging both 'the lug |81 and a lug |89 forming part of disc |80 and bent at right angles to the plane of disc |80 adjacent lug |81, both lugs being offset to prevent interference between a lug |90, forming part of disc |80, and lug |84. A spring pressed pawl |9| mounted in the lower end of lever |85 adjacent lug |84, coacts with the latter to prevent rotation of disc |80 in either direction.

The driving elements |18, |19, and their associated discs |80, together with pawls |8| constitute two one-revolution clutches, controlled by magnets acting upon armatures |9| secured to the upper ends of levers |85. The left hand clutch (Figs. 4 and 5) is controlled by a magnet SM, hereinafter called the letter spacing magnet, while the right hand clutch is controlled by a magnet BSM and will be termed the back spacing magnet. The magnets SM and BSM are mounted on brackets |03a and |04a carried by back plate |03 and front plate |04, respectively. The `corresponding clutches will be termed the letter spacing clutch and back spacing clutch, respectively, for sake of brevity.

Due to the fact that shafts |16, |11 are rotated in opposite directions by bevel gears |61, |68, the positions of corresponding parts of the letter spacing and back spacing clutches are reversed but the parts are alike in all other respects.

The lugs |90 carry pins |90a (Figs. 13 and 14) which are adapted to ride in radial slots |92 formed in plates |93 which have the general shape of a Maltese cross. Normally each pin |90a occupies the position shown in Fig. 13 in which said pin is partly in one of the slots |92. The curved parts |93a of the plates |93 coact with a curved locking plate |80a secured to one side of disc |80. The plates |93 and associated discs |80, with the pins |90a and locking plate |80a, constitute irreversible Geneva gearing which has the ratio 1:4, that is, one revolution of each disc |80 causes 1A of a revolution of each plate |93.

The plates |93 are secured, in the case of the left-hand or letter spacing clutch, to a stub shaft |94, (Figs. 13 and 14) journaled in a bushing |95 xed to frame |02a, and, in the case of the back spacing clutch, to a shortshaft |940, `iournaled in frames |02c and |02d (Fig. 4). The shafts |94, |94a have secured thereto pinions |96 (Fig. 4) which mesh with gears |91 loosely munted on shaft |14. Secured to each gear |91 is a bevel gear |98 which meshes with two bevel pinions |99 journaled in a gear 200 also loosely mounted on shaft |14. The gear 200 meshes at all times with a rack 20| secured to the upper side of one of the grooved rails |06 Asupporting and providing a guide or track for the printing unit in its movements axially of the platen.

The gears |91 to 200 constitute differential gearing whose purpose is to move the printing unit from left to right and vice-versa under control of magnets SM and BSM. Normally, however, since both gears |91 are locked (due to the fact that the Geneva gear connections associated with such gears are locked and irreversible), movement of the printing unit in either direction is positively prevented. The operation of the above mechanism will now be described briefly.

Energization of magnet SM causes lever to rock counterclockwise to disengage lug |84 from the lugs |81, |89, releasing disc |80 and driving pawl |8| which will then be drawn by its spring |83 toward shaft |16 so that lug |82 will be caught by a tooth in the constantly rotating driving element |18. The latter will now rotate disc |80 in a clockwise direction (Figs. 5 and 13) and during the first quarter revolution of disc |80 the pin |a, carried thereby will ride in the slot |92 in plate |93 and turn the latter a quarter revolution before said pin leaves the slot |92 in plate |93. Thereafter one of the locking surfaces |930, will coact with locking plate |800. to prevent further movement of plate |93 for the next three-quarters of a revolution of disc |80.

Assuming magnet SM has been deenergized immediately after operating lever |85, the latter will be Operated by its spring |88 to replace lug |84 in the paths of lugs |81, |89. Near the end of the single revolution of disc |80 the lug |84 will strike the lug |81 and rock pawl |8| out of engagement with the driving element |18. The lug |89 will also strike the lug |84 and the free end of pawl |9| will snap behind the lug |89 to hold the disc |80 in normal position and prevent rebound.

The ratio of the gearing is such that the quarter revolution imparted to plate |93 will cause gear 200 to be rotated clockwise (Fig. 5) the distance' between two successive teeth on the rack 20|, that is, the printing unit will move to the right a distance equal to one letter space. This movement of gear 200 can take place because the righthand gear |91 (Fig. 4) is locked. The energization of magnet BSM causes a similar operation of the right-hand or back spacing clutch, but in this case the right-hand gear |96 will be rotated in a direction opposite to the rotation of the left-hand gear with the result that gear 200 will likewise move in a direction opposite to that caused by the left-hand gear |98 and the printing unit will be moved one letter space distance to the left.

It will be noted that the speed of rotation of each plate |93 under the influence of its pin |90 is not uniform but is variable, ranging from zero at the starting position of pin |90a in Fig. 13 to a maximum after 1A; of a revolution of disc |80 and plate |93, and falling to zero at the point where pin |90 leaves slot |92, that is, after A revolution of plate |93 and disc |80. Thus, the motion of the printing unit is first gradually accelerated from a position of rest, then decelerated to a position of rest so that the movement of the printing unit in letter spacing and back spacing is accomplished without shock. As will be explained more fully hereinafter, the tabulating and return movements of the printing unit are brought about by the mechanism controlled by magnets SM and BSM, hence it is plain that the Geneva driving connections from the two clutches to the differential gearing render rebound devices or shock absorbers unnecessary.

The manner in which the type wheel |4 is operated to effect printing of capital letters will now be explained. It will be recalled that shaft ||5 to which the type wheel |4 is secured, is slidably mounted in frames 90, 99, |00 and has secured to it gear |23, and that normally the upper end of printing hammer |3| is in the plane of the lower case type elements ||8a. The type wheel ||4, shaft ||5, and gear |23 are thus shiftable as a unit a distance sufficient to place upper case type elements ||8 in position to be struck by the printing hammer |3| and this movement is accomplished by a case shift magnet CSM mounted on the frame 99. The magnet CSM actuates an armature 202 secured toa forked shift lever 203 pivoted on a bracket 204 secured to frame 99. The tines of the fork carry anti-friction rollers which project into a circumferential groove in a collar 205 secured to shaft ||5. A coil spring 208, secured to the right-hand end of lever 203 and to frame |00, holds the shift lever in normal position. The idler gear |24 is wide enough to permit gear |23 and type wheel |44 to move to upper case position when magnet CSM is energized, without demeshing gears |23, |24.

commutator device The selection of the type element to be operated and the energization of magnet 'PM are controlled by the character keys through the operation of the commutator device 59. The specific details of construction of the commutator device are of little importance as a number of equivalent forms may be used. The principle upon which selection is based may be best understood by reference to Fig. 9 which shows a perspective view of one form of commutator device suitable for use in an electric typewriter constructed in accordance with the present invention.

Mounted upon shaft 58 is a suitable drum 201 of insulating material carrying a plurality of conductor rings 208, one for each character key. Also mounted upon the drum is a selecting commutator S having as many conducting bars 209 as there are rings 208 and character keys. Each ring 208 is connected to one of the bars 209 and the latter are arranged on the commutator S in the same order as the pairs of type elements ||8, ||8a appear on the type wheel ||4. Co-acting with each ring is a wiping brush 2 0 which is connected to the upper contact member 36 (Fig. 2) corresponding to the character key associated with such ring. Thus for each character key there is a pair of contacts like Kb (Fig. 2), a brush 2|0, and a bar 209. A brush 2| wipes over the bars 209 of commutator S and is so positioned as to make contact with the bar 209 corresponding to a given character immediately prior to the time when the type element ||8 or ||8a bearing such character reaches the printing point. The brushes 2|0 are mounted on a bar 2|2 (Fig. 2) of insulating material secured to suitable bosses or brackets on the rear face of frame |8 while brush 2|| is secured to a block 2|3 of insulating material mounted on a boss or bracket on the rear face of frame |8. Only a few of the contacts which, like Kb are closed by depression of character keys, have been shown in Fig. 9, and each has been designated by the letter K and a suffix denoting which character key operates the contacts. The contacts closed by the shift key 24, back space key 26, return key 21, line space key 28, and tabulating key 29, have been designated in Fig. 9 by the letters SK, BSK, RK, LSK, and TK, respectively, the letters prexed to the letter K, indicating the nature of the control effected by such contacts.

Certain relays and magnets controlled by the last named contacts have been designated by the letters R and M, respectively, prefixed with the same letters as those prefixed to the related K contacts which control said relays and magnets.

General operation.

The general operation of the machine will be explained briefly prior to describing certain special features of the invention. It will be assumed that the main switch MS and non-repeat switch NRS are open, switch ARS closed, and the plug P has been inserted in the nearest receptacle connected to a suitable source of current. The locking m-agnet LM is deenergized so that bar 46 prevents depression of any of the keys. When switch MS is closed however, the bar 46 will be moved as described before herein to permit depressing of any key. It will also be assumed that only the B key is now depressed, closing contacts Kb (Figs. 2 and 9) and resulting in the depressed B key lever 30 being held depressed by the bar 40 as described. Contacts NRC will likewise be closed by the depression of the bail 5|, 52, but, as switch NRS is open, will have no effect.

Closure of contacts Kb (Fig. 9) connects the bar 209 corresponding to the B type element to the left-hand line wire 2|4 making such bar live. Eventually the live bar 209 will pass beneath the brush 2| which will Loccur a brief period of time before the b type element ||8a reaches the printing point. A circuit will now be set upas follows: Line wire 2l4,`contacts Kb, a brush 2|0 and a contact ring 208, the B bar 209, brush 2| contacts 2|5, 2|6, 2I1 of relays TR, RR, and

PR, respectively (all normally closed) one of the bars |01 and its brush |08, printing magnet PM, the lowest brush |08 and its bar |01, to righthand line wire 2 |48. Energization of the magnet PM causes the printing hammer to be operated to strike the b type element |I8a in the manner previously described. The brush'2ll is so positioned that the printing hammer will be effective to strike the b type element a sharp blow at the instant said element reaches the printing point. The printing hammer is then instantly withdrawn, as described, before it can interfere with the rotation of the type wheel H4.

During the movement of link |5I to the left (Fig. 2) contacts SC are closed thus setting up a circuit as follows: Line wire 2|4, a bar |01 and its brush |08, contacts SC', another brush |08 and coacting bar |01, the winding of the letter spacing relay SR, contacts 2 9 of the letter spacing relay, tabulating stop contacts TSC (closed), a bar |01 and its brush |08, letter spacing magnet SM, the lowest brush |08 and its bar |01, to right-hand line wire 2|8. The energization of relay SR causes its contacts 220 to close before its contacts 2|9 open, thus setting up a momentary holding circuit for the winding of relay SR from line wire 2| 4 through contacts SC and winding of relay SR, contacts 220, to line wire 2|8. This action insures that only one impulse of brief duration will be given relay SR and magnet SM. The opening of contacts SC by restoration of the link |5| causes relay SR to become deenerglzed. The release magnet RM will be energized at the same time as magnet PM since the release magnet is in parallel with magnet PM over a shunt circuit leading from contacts 2|6, through the winding of release magnet RM and Switch ARS to line Wire 2|8.

The energization of magnet RM rocks bar 40 to release the depressed key. Also a lug 22| on the bar 40 operates to close contacts 222,'the purpose of which will be explained l-ater. Energization of letter spacing magnet SM in the foregoing fashion causes the letter spacing clutch to become engaged with the result that the printing unit will be moved one letter space distance to the right (Fig. l).

It should be noted that if any character key is held down by the operator while switch ARS is closed, the character correspondingto such key will be repeatedly printed as long as the key is held down. If switch ARS is opened and a character key, such as the B key, depressed once, the key lever 30 of the B key will remain locked in depressed position with the result that the letter b will be automatically printed as many times as desired since the circuit to the release magnet RM will be interrupted and the contacts Kb will be held closed. When the operator desires to interrupt such automatic repeat printing, it will be merely necessary to move switch ARS to the off position (Fig. 1) or closed position (Fig. 9).

bodying the above novel features of the present invention.

The automatic repeat printing is very undesirable in ordinary writing operations when words or numbers are being printed or sentences typewritten, as the failure of the operator to release an operated key promptly may cause a double or triple imprint of a character thus spoiling the work and requiring an erasure.V` Such repeated printingis prevented by the non-repeat contacts NRC and the printing relay PR which operate to prevent a second imprint from the type wheel when the operator inadvertently holds a key de pressed or fails to remove a finger from a key quickly enough. The contacts NRC (Figs. 2 and 9) remain closed as long as any character key is in depressed position. Ordinarily no circuit can extend through contacts NRC and PR since normally they are in a series circuit including contacts 222 operated by release magnet RM. When magnets PM and RM are energized in the course of a printing operation, contacts 222 close momentarily and acircuitis established from line wire 2|4, contacts NRC, switch NRS, Winding of print relay PR, and contacts 222, to line Wire 2|8. The circuit through the release magnet RM will be held through the active bar 209 and brush 2|! until the brush 2|| breaks contact with said bar. Thus, the release magnet will be kept energized long enough to ensure that the depressed key will be fully released. Energization of print relay PR closes contacts 223-and opens contacts 2|1 so that the circuit for magnetPM is broken immediately after the energization ofsaid magnet and at the same time a holding circuit for print relay PR is established through contacts NRC and 223.

It is clear that, as long ascontacts NRC are kept closed as by the operator holding a character key depressed, the relay PR will remain energized and prevent another operation of magnet PM. When a character key is held down too long, the

relay PR will function as above with the result that magnet RM will be energized each time the active bar 209 passes beneath brush 2| but the magnet PM can not receive an impulse. It is plain, therefore, that repeated printing is impossible as long as any key is held down since magnet PM can receive a single impulse for each depression of a key. When the operator removes his finger from the depressed key, the magnet RM will receive one more impulse (since the depressed keyis still held down by its lug 39 and bar 40) which will effect release of the depressed key and permit contacts NRC to open and inter:

rupt the circuit to magnet PR. It is preferred that contacts NRC be adjusted to remain closed at least until after the character key controlled contacts like Kb have opened on the upward stroke of the depressed key in order to avoid the possibility of contacts 2|1 closing before contacts like Kb have opened.

The space bar 23 is mounted on the free ends of key levers 30a (Fig. 2) like the key levers 30, except for the omission of lugs 39 and 43, and the levers 30a do not overlie bail 5|, 52. The lugs on the key levers 30ar operate to close contacts SK (Fig. 9) which are in parallel. The contacts SK are also in parallel with contacts SC which it will be recalled control the magnet SM. It is quite apparent that closure of contacts SK by depression of space bar 23 will have the same effect as closure of contacts SC.

The back spacing key 28 controls contacts BSK and when depressed energizes back spacing relay BSR and the back spacing magnet BSM over a circuit as follows: Left-hand line wire 2|4, contacts BSK, winding of relay BSR, contacts 224, of relay BSR, return stop contacts RSC (normally closed) bar |01 and brush |08, magnet BSM, the lowest brush |08 and its bar |01, to right-hand line wire 2|8. Energization of magnet BSM causes the back spacing clutch (Fig. 4) to be engaged to cause the printing unit to move one letter space distance to the left (Fig. 1). Energization of relay BSR causes its contacts 225 to close before contacts 224 open and the contacts 225 establish a momentary holding circuit for relay BSR to line wire 2|8 exactly as in the case with relay SR previously described. Thus a single impulse of current is imparted to magnet BSM.

Tabulating and returning printing unit 'I'he mechanism illustrated in Figs. 4 and 5, controlled by magnets SM and BSM, are also jointly controlled in a novel fashion by three keys and a single stop bar to cause tabulating movement of the printing unit, returning the printing unit to starting position to begin a new line, and line spacing movement of the platen. All these movements are automatically controlled by only three contacts operated by the single stop bar. This mechanism is best understood by reference to Figs. 6 to 9. Secured to the shaft 3|, on which.

are pivoted key levers 30, are two arms 226 (Figs. 6 and '7) which extend vertically into the space in front of frame |8 adjacent frames |0, (see Fig. 2 also). Springs 221 normally hold the arms 226 against fixed pins 228 carried by frames I0, A stop bar 229 is slidably mounted in rectangular holes 230 in the free ends of arms 228. The stop bar is provided with notches 23| spaced at intervals of one letter space distance which notches are adapted to retain stops like 232, 233, 234 (see Fig. 8) of which 232 and 234 are the left-hand and right-hand marginal stops, respectively, while 233 is a tabulating stop. These stops extend forwardly of the bar 229 (or to the right, Fig. 2) into the path of a cam lug 235 on a block 236 secured to the rear of the printing unit.

The right-hand end (Fig. 6) of bar 229 is provided with a pin 231 which, through movements of bar 229, controls three sets of contacts ARC, RSC, and TSC which are mounted on insulating blocks carried by a frame 238 secured to frame The above contacts may be termed the automatic return contacts, return stop contacts, and tabulating stop contacts, respectively. The contacts TSC are directly operated by pin 231 and are opened whenever bar 229, and arms 226 are rocked rearwardly or clockwise (Fig. 7). The contacts ARC and RSC are operated by two levers 240, 24| which extend on opposite sides of pin 231 and are both pivoted on a screw stud 242 carried by frame 238.

A strong coil spring 243 normally holds both levers 240, 24| firmly against a fix-ed stop 244 .fixed to frame 238 and said stop is just wide enough to permit pin 231 to move freely laterally of the axis of the bar 229 but prevents longitudinal movement of bar 229 unless by a force sufficient to overcome the tension of spring 243. When the bar 229 is moved to the right (Fig. 6) normally open contacts ARC will be closed by movement of lever 24|. On the other hand, normally closed contacts RSC will be opened by lever 240 whenever bar 229 is moved to the left. The three movements of bar 229 to control the three sets of contacts are controlled by the three types of stops shown in Fig. 8. Their operation in conjunction with the keys 21, 29 will now be explained in detail.

As many stops as may be necessary will be set in the usual fashion to correspond with the various columns of the sheet on which typewritten data is to appear in columnar form, bar 229 being provided with the usual scale for convenience in locating the stops 233 the proper number of letter spaces distance from the left-hand limit of movement of the printing unit. Assuming that the operator wishes to typewrite data in one of the columns having a stop 233, he will depress tabulating key 29, thus closing contacts TK and energizing tabulating relay TR over a circuit as follows: Left hand line wire 2|4, contacts TK, winding of relay TR, tabulating stop contacts TSC, a bar |01 and its brush |08, magnet SM, the

lowest brush |08 and its bar |01, to line wire 2|8. Relay TR closes its contacts 245 to establish a holding circuit for itself around contacts TK. permitting key 23 to be released, and opens contacts 2 5, in series with magnet PM, to prevent a printing operation from taking place.

The energization of magnet SM causes the letter spacing clutch to be engaged and the printing unit will commence to move to the right (Fig. l). Since magnet SM is kept energized by the holding circuit through contacts 245, the letter spacing clutch will not become disengaged after the first revolution of shaft |16 but will remain engaged.

The printing unit will continue its movement to the right until cam lug 235 strikes the bevelled edge of one of the stops 233, thus forcing bar 229 rearwardly (to the right Fig. 7) and opening contacts TSC. As a result the relay TR and magnet to be struck by the flat side of the cam lug 235 so as to slide the bar 229 whenever the printing unit in its movements reaches the limits of movement determined by said stops.

Assume that in the course of writing a line of typewritten matter the cam lug 235 strikes stop 234 thus forcing bar 229 to the right (Fig. 6) and causing lever 24| to close automatic return contacts ARC. This causes a circuit to be established as follows: Left hand line wire 2|4, contacts ARC, winding of return relay RR, return stop contacts RSC, a bar |01-and its brush |08, back spacing magnet BSM, and the lowest brush |08 and its l Automatic l'ine spacing Relay RR also closes contacts 241 which, in

` collaboration with contacts 246 establish a circuit as follows:-. Line 2|4, contacts 245, 241, winding of line space relay LSR, contacts 248 of relay LSR, and the line spacing solenoid LSS, to line wire 2| 8. Relay LSR closes its contacts 249 to establish a holding circuit for itself to line wire 2||l and opens to contacts 248 to break the circuit through the solenoid LSS so that the llatter receives a single impulse. Relay LSR is preferably a slow acting relay and its contacts 249 close before contacts 248 open in order to insure that solenoid LSS will receive a single impulse of duration suflcient to cause a complete operation of the line spacing mechanism. Relay LSR becomes de-energized as soon as contacts RSC open. Contacts LSK, controlled by the line spacing key LSK, have the same effect as contacts 246, 241, while contacts RK, controlled by the return key 21 have the same effect as contacts ARC. Thus the operator can line space the platen at any time by merely depressing key 28 or can both line space the platen and return the printing unit by depressing key 21.

'I'he printing unit 65 is provided with a suitableindex finger or pointer 250 secured to the front plate |04 which pointer coacts with a scale 25| on the upper edge of the front plate 1 to indicate the exact position of the printing unit at all times.

Automatic operation of a line, returning the printing unit to begin a new line, and resuming the printing of the desired character on the new line, all automatically performed and initiated by depression of a single key.

Assume it is desired to block out four lines of a printed form with a row of Xs. Automatic repeat switch ARS is thrown to on or open position and the X key depressed. The niachine will now automatically print a row of XIs until eventually lug 235 strikes stop 234 thus closing contacts ARC to initiate return of the printing unit to starting position as described.

Contacts 2|0 of relay RR will open preventing the printing magnet PM from operating at the end of the line and while the printing unit is being returned. The magnet RM, not having been energized to release the depressed X key, the latter will still be locked in depressed position by bar 40 and contacts Kx will be closed when eventually the printingunit arrives at its starting position in readiness to begin a new line at which point contacts RSC open to deenergize relay RR and magnet BSM. Reclosure of contacts 2|6, by the deenergization of relay RR. will complete a circuit to magnet PM through contacts Ka: and the machine will resume automatic printing of the Xs. The above action will continue as long as switch ARS is open. When the fourth line is almost completed the switch ARS is closed by the operator causing magnet RM to be ener gized to release the depressed key.

Since the machine is capable of printing more rapidly than the operator can operate the keys a considerable amount of time is saved besides saving the operators energy for work requiring closer manual supervision by the operator.

Relays TR, and RR, through their contacts 2|5, 2|6 positively prevent operation of the printing mechanism during tabulating and return movements of the printing unit.

The machine described herein is much simpler than prior power driven typewriters because the print-ing mechanism comprises a single type wheel which is controlled by contacts actuated by the keys rather than by linkages operated by the keys. The elimination of the usual pivoted type bars with their individual Voperating cams or actuators, common in prior power driven typewriters, permits a considerable saving in the cost of the machine.

The fact that the present machine is wholly controlled by contacts actuated by the keys admirably adapts it for use in printing telegraph systems and automatic letter writers controlled by perforated tapes. In the one case the brushes 2|0 can be directly connected to a suitable coding or decoding device in the telegraph system while in the other case the brushes 2|0 can be directly connected to the analyzer sensing the holes in the tape. In either of the above cases the necessary connections need not interfere to the smallest degree with manual control of the machine through the keyboard. Y

The printing mechanism described herein has been found by actual experiment to produce a fio clear impression even with the type wheel moving relative to the paper. It is quite possible, therefore, to adjust contacts SC to close and initiate operation of the spacing clutch before the printing hammer strikes the selected type element so that printing and letter spacing take place together thus producing a faster operation than will be realized when the letter spacing operation must not take place untilafter the vimpression of the type has been made. It is also possible to energize magnets PM and SM simultaneously or even energize magnet SM first since the initial movement of the plate |93 and shaft |94 is slow whereas the printing'hammer |3| operates at high speed.

While there has been shown and described and v pointed out the fundamental novel features of the invention as applied to a single modification, it

will be understood that various omissions and substitutions and changes in the form and details of the device illustrated in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to be limited only as indicated by the scope of the following claims.

What is claimed is as follows:

l. In combination, recording mechanism, a power drive adapted to operate the recording mechanism, including an electric propulsion unit, a series of circuit closing devices selectively operable to control recording operations of the recording mechanism by the power drive, means operative to prevent operation of the circuit closing devices, and an electro-magnetic current responsive device for rendering the preventing means inactive when current is supplied to the propulsion unit.

2` A typewriting machine comprising printing mechanism, a power drive for said mechanism including a driving motor, a series of selectively operable devices for controlling the operation of the printing mechanism by the power drive, and electro-magnetic means controlled directly by the current supply to the motor for preventing operation of said devices when the flow of current to the motor ceases.

3. In combination with a main frame and a work sheet support mounted on the frame; of a self-contained printing unit movably mounted on said frame whereby the printing unit is adapted to traverse a work sheet on said support, said printing unit comprising a printing element with power means for selectively actuating the printing element to print upon the work sheet and power means for moving the printing unit stepby-step relative to the work sheet whereby the printed characters are spaced on the work sheet; and means independent of the printing unit for controlling thc selective actuating means and moving means.

4. In combination, recording mechanism, a power drive for operating the recording mechanism, means for selectively controlling the operation of the recording mechanism by the power drive including a plurality of selectively operable circuit closing devices and a printing magnet, means for preventing more than one operation of said magnet for each operation of a circuit closing device to prevent repeated recording operations when a circuit closing device is kept in operated condition too long, and means for disabling the preventing means to permit repeated operations of the magnet when a selected circuit closing device is held in operated position.

5. In a typewriting machine, a stationary work sheet support, a printing unit adapted to traverse a work sheet on the support, said printing unit having a sliding driving connection to the motor and comprising means for printing on the Work sheet including a type wheel having two rows of characters, means for moving the printing unit from one side of the sheet to the other to print characters in succession, means for shifting the type wheel to select one of said rows of characters for a subsequent character selecting operation, and power means for selecting from the selected row the character which is to be effective to print; said type wheel, moving means, and selecting means all being operated through the sliding connection.

6. A typewriting machine comprising a power drive, printing means adapted to be operated by the power drive, a series of manually operable keys for selectively controlling operation of the printing means by the power drive, means common to all the keys to prevent repeat operation of the printing means when a key is kept in operated position for too long a period, means releasable by an operation of the printing means for locking any selected key in operated position, and auxiliary means also common to all the keys for rendering the rst named means ineffective whereby to permit repeat printing under control of any active key.

7. In a typewriting machine, a propulsion unit, a power shaft driven by said unit, a stationary support for a work sheet, a self-contained printing unit movable from one side ofthe work sheet to the other to print a line of characters in succession, said unit comprising a constantly rotating power-driven type wheel having two rows of characters, means for actuating the type wheel to eiect selection of a row of characters, means cooperating with the type wheel to effect selection of a character in the selected row, and means operable to move the printing unit from any point in a line to another point in the same line, said type wheel, operating means, and moving means being all mounted in said unit and having a sliding connection to the power shaft to permit the printing unit to move from. one side of the work sheet to the other to print a line of characters; and means external to said unit and independent of its movement for controlling the actuating means and moving means.

8. In a typewriting machine, a support for a record sheet, and a self-contained printing unit movable parallel with said support to print a line of characters; said unit comprising a constantly rotating type wheel, power means cooperating with the type wheel to select a type and make an impression on the record sheet while the type wheel is in motion, and means for moving the printing unit from one point in a line to another including a differential gear device and selective clutch means for controlling said device to determine the direction of movement of the printing unit; a propulsion unit, a shaft constantly driven l by said propulsion unit, said shaft extending parallel with the line of travel of the printing unit and having sliding driving connection to the type-wheel and associated means included in the printing unit. A

9. A typewriting machine comprising printing mechanism, a .power drive for the printing mechanism, character keys operable to connect the printing mechanism to the power drive to print characters corresponding to the keys, means for preventing a second printing operation when any key is held in operated position until after a single character has been printed, means for retaining an operated key in operated position, means eiective during a printing operation to release the retaining means, and a device for rendering inactive both the preventing means and the releasing means.

10. In a typewriting machine, a stationary support for a work sheet; a self-contained movable printing unit adapted to traverse the work sheet and its support to print a line of writing, said printing unit comprising a constantly moving type element, power means operable to select a type for an impression while the type element is moving, a magnet for controlling the power means, means moving the printing unit including differential gears, and an element controlled by the first-named means for rendering the difierential gears effective to move the printing unit as an incident to a type selecting operation; and devices external to the printing unit and independent'of its movement for controlling the magnet.

11. A typewriting machine comprising a power drive, printing means adapted to be operated by the power drive; a series of manually operable elements, each element representing a character and adapted to be selectively operated to control operation of the printing means by the power drive to print the character said element represents; means for locking said elements in operated position, means operable as an incident to each printing operation to disable the locking means to permit return of the operated elements to normal position, and a manually operable device for disabling the last named means to permit a second operation of the printing means.

12. In a typewriting machine, a printing instrumentality, a power drive therefor, and means operated by the power drive for moving the printing instrumentality in two directions comprising differential gearing, a pair of lirreversible Geneva gear connections each operating the differential gearing in a diierent direction, a pair of clutches, each adapted to couple one of said gear connections to the power drive, and selecting means for controlling the operation of the clutches.

13. In a typewriting machine, a power drive, a work sheet support, and a movable printing unit adapted to traverse a work sheet on said support; said printing unit comprising a type Awheel constantly rotated by the power drive, means operated by the power drive for taking an impression from the type wheel while it is in motion and without interrupting its motion, and means for moving the printing unit after each impression to traverse the work sheet.

14. In a typewriting machine, a power drive, a work sheet support, a series of keys, and a movable printing unit adapted to traverse the work sheet; `said printing unit comprising a constantly rotating type wheel, a printing hammer, a driving ratchet constantly operated by the power drive, an inter-ponent connected to the printing hammer and adapted to engage the teeth of the driving ratchet, a latch holding the inter-ponent in idle position, an electromagnet controlled by said keys and adapted to release said latch to cause an impression, and means operated by the power drive for advancing the printing unit after each impression.

15. In a typewriting machine, a work sheet support, a printing unit movable to traverse a work sheet on the support, means for moving the printing unit in either direction to traverse the work sheet; a control element operable in response to movement of the printing unit, said element extending parallel with the path of movement of the printing unit and movable in three different directions, and a control unit operated by the movements of said element for controlling movement of the printing unit in both directions.

16. In a typewriting machine, a movable printing unit, and means for moving said unit in opposite directions comprising a fixed rack, a -differential gear device engaging said rack and mounted in said unit, a power drive, a pair of clutches for connecting said power drive to said differential gear device to operate the latter in two different directions, a stop bar extending parallel with the path of movement of the printing unit and movable in three directions by movement of the printing unit, and means conl trolled by the movements of said stop bar for selectively operating said clutches.

17. A typewriting machine comprising a printing instrumentality, a work sheet support, the latter `and said printing instrumentality being movable relative to each other to prlnta line of characters on a work sheet on the support; means for causing said movement including a rack, a device geared to the rack for moving the printing instrumentality and support relative to each other in two directions, a power drive and a pair of clutches selectivelyV operable to connect the power drive to the reversible device to operate the latter in two directions; a stop bar movable in three directions in response to movements of the printing instrumentality and support relative to each other, and a pair of electric control circuits, one for each clutch, for selectively operating the clutches in accordance with the movements of the stop bar.

18. An electric typewriter comprising a main frame, a work sheet support mounted in the main frame, guides mounted in the frame and extending parallel with the work sheet support, an electric motor; a drive shaft rotatably mounted in the frame and extending-parallel with the guides, said shaft being continuously driven by the motor; a carriage mountedon said guides to traverse a Work sheet on Athe support, a hollow drive shaft mounted in the carriage and having a sliding driving connection to the rst drive shaft, a type wheel driven by the hollow shaft and mounted in the carriage, a printing hammer coacting with the type wheel and operating means therefor operable by the hollow drive shaft, electromagnetic means on the carriage for controlling the operation of the printing hammer, means operable by the hollow drive shaft for moving the carriage after each impression, electromagnetic means controlled by movement of the 1 printing hammer for controlling the operation of the carriage moving means by the hollow drive shaft, a series of contact rails mounted in the main frame and extending parallel with the guides; contact elements mounted on the carriage and coacting with the contact rails, said contact elements being connected to the electromagnetic means on the carriage; a series of manually operable control keys mounted in the main frame, circuit controlling devices operated by the keys, and control circuits connecting said devices to the contact rails.

19. A printing machine comprising a main frame, a work sheet support mounted in said frame, a carriage slidably mounted in said frame for traversing a work sheet on said support; power operated printing means, character selecting means, and carriage traversing means all mounted in said carriage; an electric propulsion unit mounted in the main frame, a single operating shaftI continuously operated by said unit and extending parallel with the movement of the carriage; a sliding connection in the carriage between said shaft and power operated means on the carriage, electromagnet control devices on the carriage for controlling the operation ofthe power operated means, contact rails mounted on 20. In a typewriting machinaa main frame,

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a work sheet support mounted in said frame, a printing unit mounted in said frame for movement to traverse a work sheet on said support, an electric propulsion unit, a shaft continuously driven by said unit and extending parallel with the work sheet support, a rack mounted in said frame and parallel with said support; a differential gear device meshing with said rack and mounted in the carriage, said gear device including a pair of normally disengaged one revolution clutches connecting said differential gear device with the continuously driven shaft, one

of said clutches when engaged, causing the dif--Y ferential gear to be rotatedin a direction to move the carriage toward the right for letter spacing or tabulating movement and the other clutch when engaged causing the carriage to move to the left for back spacing or carriage return movement; and electromagnetic means associated with said clutches for selectively engaging them.

21. In a typewriting machine, a work sheet support, a printing unit movable to traverse the work sheet support, a rack parallel with the line of travel of the printing unit, and means mounted in the printing unit for moving the printing unit comprising a gear meshing with the rack, a pair of bevel gears rotatably mounted in the printing unit on each side of the rst named gear, idler gears on the first named gear and connecting said bevel gears, a continuously operated drive shaft mounted in the printing unit; a pair of irreversible Geneva drive units, each connected to one of said bevel gears whereby rotation of the first named gear and hence the printing unit is normally prevented; a pair of one revolution clutches, each adapted when engaged to connect one of the Geneva drive units to the power drive shaft, and a pair of electromechanical devices, each associated with a clutch for selectively engaging the clutches.

22. In a typewriting machine, a power drive, a work sheet support, and a movable printing unit adapted to traverse a work sheet on said support, said printing unit comprising a type wheel constantly rotated by the power drive, power means operated by the power drive for taking an impression from the type wheel while it is in motion and without interrupting its motion, means operated by the power drive for moving the printing unit a letter space distance for each impression and means operated by the impression taking means for initiating an operation of the moving means.

23. In a typewriting machine, recording mechanism, power means for operating the recording mechanism including an electric propulsion unit, keys for controlling the operation of the recording mechanism by the power means, a locking bar common to all the keys and movable to a position to lock all the keys against operation, and electromagnetic means controlled directly by the current supplied to the propulsion unit for operating the locking bar.

24. In a typewriting machine, a traveling carriage, a stop bar extending parallel with the line of travel of the carriage and adapted for movement in two directions along its longitudinal axis and also movement transverse of its longitudinal axis, marginal stops settable on the carriage and engageable thereby to cause longitudinal movement of the stop bar in the direction of movement of the carriage, a tabular stop engageable by the carriage to cause transverse movement of the stop bar, and carriage moving means selectively controlled by the movements of the stop bar caused by said stops.

25. In a typewriting machine, a traveling carriage, a. xed rack along which the carriage moves; a constantly rotating power shaft parallel with the rack, a carriage moving device mounted in the carriage including a diierential gear device meshing with said rack and adapted to drive the carriage in either direction along said rack. and including a pair of selectively actuable clutches connecting the gear device to the power shaft for driving purposes; a stop bar movable in two directions longitudinally of its axis and also movable transversely of its axis, said stop bar being adapted by such movements to selectively control the clutches; and stops settable on the stop bar and responsive to movement of the carriage, each stop being adapted to cause movement of the bar in one of said directions.

26. In a typewriting machine, printing mechanism, a series of character keys for controlling said mechanism, means for locking the keys in operated position, means controlled by the print-' ing mechanism for releasing said lockl and means controlled by the releasing means for preventing a second operation of the printing mechanism before a subsequent key operation.

27. In a typewriting machine, printing mechanism, a series of character keys for controlling said mechanism, means for locking the keys in operated position, means controlled by the printing mechanism for releasing said lock, means controlled by the releasing means for preventing a second operation of the printing mechanism before a subsequent key operation, and manually operable means for disabling both the releasing means and the preventing means to enable repeated printing in response to operation of any selected key.

28. An electric typewriter comprising a printing circuit, a series of keys and selecting means controlled by said keys for controlling said circuit, a traveling carriage, means for returning the carriage, a carriage return key for controlling the carriage return means, and means controlled by the carriage return key for interrupting the printing circuit while the carriage is being returned.

29. In a typewriting machine, power operated printing mechanism including a printing circuit and a selectively controllable printing magnet; a traveling carriage, means for moving said carriage to space characters printed by the printing mechanism, a magnet controlled by operation of the printing mechanism for initiating an operation of the moving means, a tabular key, means controlled by the tabular key for controlling the second magnet, and means also controlled by the tabular key for interrupting the printing circuit to prevent operation of the printing magnet during tabulating operations.

30. A recording machine comprising a power drive, recording mechanism operable by the power drive, selecting members for selectively controlling the operation of the recording mechanlsm by the power drive, means associated with the selecting members for preventing more than one operation of the recording mechanism at a time when any selecting member is operated, means automatically released during each operation of the recording mechanism for holding the selecting members in operated position, and a device for renderingl ineffective both the holding means and preventing means whereby to permit automatic repeated operation of the recording mechanism under control of an operated selecting member.

31.` lIn combination, recording mechanism, power means to operate the recording mechanism, a series of control devices selectively operable to control operationof the recording mechanism by the power drive, means for preventing more than one operation of the recording mechanism when any selected control device is operated, means to hold the selected control device in operated position, means automatically operative during each recording operation for releasing the holding means, and a device settable to connecting the power means to the propulsion unit and adapted to permit the carriage to move freely on the frame, control devices on the carriage for determining the direction of movement imparted to the carriagel by the moving means, and means for selectively controlling the control devices including a stop bar having marginal stops for controlling the limits of travel of the carriage, and a stop for limiting tabulating movement and including keys for controlling the movements of the carriage.

34. In a typewriting machine, a main frame, a Work sheet support on said frame; a travelling render ineifective both the holding means ank/carriage comprising a type wheel adapted to print releasing means.

32. In a recording machine, a main frame, a propulsion unit mounted in the frame, a carriage movable in said frame; power means on the carriage and adapted for moving the carriage forwardly to letter space and tabulate the carriage and also adapted for moving the carriage backwardly to back-space and return the carriage;

means for connecting the power means to` the propulsion 'unit and adapted to permit the carriage to move freely on the frame, control devices on the carriage for determining the direction of movement imparted to the carriage by the power moving means, and selective' devices mounted on the frame for controlling the control devices.

33. In a recording machine, a main frame, a propulsion unit mounted in the frame, a carriage movable in said frame; power means on the carriage and adapted for moving the carriage forwardly to letterispace and tabulate backwardly to backspacing and return the carriage; means for on the work sheet and continuously power driven, power means for selecting the character printed by said type wheel, a single magnet for controlling the power selecting means; and means external to the carriage for controlling said magnet comprising a selecting commutator and a series of circuit closing devices each associated with one of the characters on the type wheel.

35. In a typewriting machine, a main frame, a work sheet support on said frame; a travelling carriage comprising a printing element constantly in motion/and adapted to print on the work sheet, power means selecting the character printed by said printing element, and an element for controlling the power selecting means; a series of character keys mounted in the frame and independent of the carriage, and means mounted in the frame and independent of the carriage for operating the controlling element in accordance with any selected key.

JAMES WARES BRYCE. ARTHUR HALSEY DICKINSON. 

